1. Field of the Invention
The present invention relates to an image formation apparatus and an image formation method for producing a copy of the image of a document on a medium. More particularly, it relates to an image formation apparatus and an image formation method for appropriate processing of any alteration, such as degradation in picture quality, damage or color change (hereinafter referred to as simply “alteration(s)”, whether it is intentional or not), occurring on an image covered by protection under a copyright or any other intellectual property right, in the document, where the alteration makes this image different from the original image.
2. Description of the Related Art
Images to be processed by an image formation apparatus include objects of an exclusive right such as a copyright (hereinafter referred to as simply “copyright”). For this reason, various techniques have been proposed by which copyrighted works (works of authorship protected by a copyright) can be protected and their reproduction can be appropriately restricted. For instance, Japanese unexamined patent publication No. 2000-196786 discloses a technique by which information on the prohibition or permission of copying can be added to printed matter by appending a digital watermark, administrative code or the like.
Japanese unexamined patent publication No. 2004-334380 discloses a technique by which the use of a given copyrighted work can be kept track of by referencing an administrative code appended to the copyrighted work. According to the technique described in this document, a semiconductor memory chip is embedded in the copyrighted work, for instance. It is claimed that, by monitoring the administrative code stored in the chip via a network, the copyrighted work can be kept under administration.
However, these known techniques involve the following problems. Since one or another of various networks is referenced for information on copyrighted works by the technique described in either of these documents, this might impose heavy loads on the network, and the processing might accordingly take a long time. Moreover, though reproduction is restricted, no mention is made of processing against any altered part in the copyrighted image to be copied. This means that, if within the limit of permitted reproduction, even an altered image could be circulated as it is.